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kern_ktrace.c revision 1.23 
      1 /*	$NetBSD: kern_ktrace.c,v 1.23 1996/02/09 18:59:36 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  *
     35  *	@(#)kern_ktrace.c	8.2 (Berkeley) 9/23/93
     36  */
     37 
     38 #ifdef KTRACE
     39 
     40 #include <sys/param.h>
     41 #include <sys/systm.h>
     42 #include <sys/proc.h>
     43 #include <sys/file.h>
     44 #include <sys/namei.h>
     45 #include <sys/vnode.h>
     46 #include <sys/ktrace.h>
     47 #include <sys/malloc.h>
     48 #include <sys/syslog.h>
     49 
     50 #include <sys/mount.h>
     51 #include <sys/syscallargs.h>
     52 
     53 struct ktr_header *ktrgetheader __P((int));
     54 int ktrops __P((struct proc *, struct proc *, int, int, struct vnode *));
     55 int ktrsetchildren __P((struct proc *, struct proc *, int, int,
     56 			struct vnode *));
     57 void ktrwrite __P((struct vnode *, struct ktr_header *));
     58 int ktrcanset __P((struct proc *, struct proc *));
     59 
     60 struct ktr_header *
     61 ktrgetheader(type)
     62 	int type;
     63 {
     64 	register struct ktr_header *kth;
     65 	struct proc *p = curproc;	/* XXX */
     66 
     67 	MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
     68 		M_TEMP, M_WAITOK);
     69 	kth->ktr_type = type;
     70 	microtime(&kth->ktr_time);
     71 	kth->ktr_pid = p->p_pid;
     72 	bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN);
     73 	return (kth);
     74 }
     75 
     76 void
     77 ktrsyscall(vp, code, argsize, args)
     78 	struct vnode *vp;
     79 	register_t code;
     80 	size_t argsize;
     81 	register_t args[];
     82 {
     83 	struct	ktr_header *kth;
     84 	struct	ktr_syscall *ktp;
     85 	register len = sizeof(struct ktr_syscall) + argsize;
     86 	struct proc *p = curproc;	/* XXX */
     87 	register_t *argp;
     88 	int i;
     89 
     90 	p->p_traceflag |= KTRFAC_ACTIVE;
     91 	kth = ktrgetheader(KTR_SYSCALL);
     92 	MALLOC(ktp, struct ktr_syscall *, len, M_TEMP, M_WAITOK);
     93 	ktp->ktr_code = code;
     94 	ktp->ktr_argsize = argsize;
     95 	argp = (register_t *)((char *)ktp + sizeof(struct ktr_syscall));
     96 	for (i = 0; i < (argsize / sizeof *argp); i++)
     97 		*argp++ = args[i];
     98 	kth->ktr_buf = (caddr_t)ktp;
     99 	kth->ktr_len = len;
    100 	ktrwrite(vp, kth);
    101 	FREE(ktp, M_TEMP);
    102 	FREE(kth, M_TEMP);
    103 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    104 }
    105 
    106 void
    107 ktrsysret(vp, code, error, retval)
    108 	struct vnode *vp;
    109 	register_t code;
    110 	int error;
    111 	register_t retval;
    112 {
    113 	struct ktr_header *kth;
    114 	struct ktr_sysret ktp;
    115 	struct proc *p = curproc;	/* XXX */
    116 
    117 	p->p_traceflag |= KTRFAC_ACTIVE;
    118 	kth = ktrgetheader(KTR_SYSRET);
    119 	ktp.ktr_code = code;
    120 	ktp.ktr_error = error;
    121 	ktp.ktr_retval = retval;		/* what about val2 ? */
    122 
    123 	kth->ktr_buf = (caddr_t)&ktp;
    124 	kth->ktr_len = sizeof(struct ktr_sysret);
    125 
    126 	ktrwrite(vp, kth);
    127 	FREE(kth, M_TEMP);
    128 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    129 }
    130 
    131 void
    132 ktrnamei(vp, path)
    133 	struct vnode *vp;
    134 	char *path;
    135 {
    136 	struct ktr_header *kth;
    137 	struct proc *p = curproc;	/* XXX */
    138 
    139 	p->p_traceflag |= KTRFAC_ACTIVE;
    140 	kth = ktrgetheader(KTR_NAMEI);
    141 	kth->ktr_len = strlen(path);
    142 	kth->ktr_buf = path;
    143 
    144 	ktrwrite(vp, kth);
    145 	FREE(kth, M_TEMP);
    146 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    147 }
    148 
    149 void
    150 ktremul(vp, emul)
    151 	struct vnode *vp;
    152 	char *emul;
    153 {
    154 	struct ktr_header *kth;
    155 	struct proc *p = curproc;       /* XXX */
    156 
    157 	p->p_traceflag |= KTRFAC_ACTIVE;
    158 	kth = ktrgetheader(KTR_EMUL);
    159 	kth->ktr_len = strlen(emul);
    160 	kth->ktr_buf = emul;
    161 
    162 	ktrwrite(vp, kth);
    163 	FREE(kth, M_TEMP);
    164 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    165 }
    166 
    167 void
    168 ktrgenio(vp, fd, rw, iov, len, error)
    169 	struct vnode *vp;
    170 	int fd;
    171 	enum uio_rw rw;
    172 	register struct iovec *iov;
    173 	int len, error;
    174 {
    175 	struct ktr_header *kth;
    176 	register struct ktr_genio *ktp;
    177 	register caddr_t cp;
    178 	register int resid = len, cnt;
    179 	struct proc *p = curproc;	/* XXX */
    180 
    181 	if (error)
    182 		return;
    183 	p->p_traceflag |= KTRFAC_ACTIVE;
    184 	kth = ktrgetheader(KTR_GENIO);
    185 	MALLOC(ktp, struct ktr_genio *, sizeof(struct ktr_genio) + len,
    186 		M_TEMP, M_WAITOK);
    187 	ktp->ktr_fd = fd;
    188 	ktp->ktr_rw = rw;
    189 	cp = (caddr_t)((char *)ktp + sizeof (struct ktr_genio));
    190 	while (resid > 0) {
    191 		if ((cnt = iov->iov_len) > resid)
    192 			cnt = resid;
    193 		if (copyin(iov->iov_base, cp, (unsigned)cnt))
    194 			goto done;
    195 		cp += cnt;
    196 		resid -= cnt;
    197 		iov++;
    198 	}
    199 	kth->ktr_buf = (caddr_t)ktp;
    200 	kth->ktr_len = sizeof (struct ktr_genio) + len;
    201 
    202 	ktrwrite(vp, kth);
    203 done:
    204 	FREE(kth, M_TEMP);
    205 	FREE(ktp, M_TEMP);
    206 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    207 }
    208 
    209 void
    210 ktrpsig(vp, sig, action, mask, code)
    211 	struct vnode *vp;
    212 	int sig;
    213 	sig_t action;
    214 	int mask, code;
    215 {
    216 	struct ktr_header *kth;
    217 	struct ktr_psig	kp;
    218 	struct proc *p = curproc;	/* XXX */
    219 
    220 	p->p_traceflag |= KTRFAC_ACTIVE;
    221 	kth = ktrgetheader(KTR_PSIG);
    222 	kp.signo = (char)sig;
    223 	kp.action = action;
    224 	kp.mask = mask;
    225 	kp.code = code;
    226 	kth->ktr_buf = (caddr_t)&kp;
    227 	kth->ktr_len = sizeof (struct ktr_psig);
    228 
    229 	ktrwrite(vp, kth);
    230 	FREE(kth, M_TEMP);
    231 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    232 }
    233 
    234 void
    235 ktrcsw(vp, out, user)
    236 	struct vnode *vp;
    237 	int out, user;
    238 {
    239 	struct ktr_header *kth;
    240 	struct	ktr_csw kc;
    241 	struct proc *p = curproc;	/* XXX */
    242 
    243 	p->p_traceflag |= KTRFAC_ACTIVE;
    244 	kth = ktrgetheader(KTR_CSW);
    245 	kc.out = out;
    246 	kc.user = user;
    247 	kth->ktr_buf = (caddr_t)&kc;
    248 	kth->ktr_len = sizeof (struct ktr_csw);
    249 
    250 	ktrwrite(vp, kth);
    251 	FREE(kth, M_TEMP);
    252 	p->p_traceflag &= ~KTRFAC_ACTIVE;
    253 }
    254 
    255 /* Interface and common routines */
    256 
    257 /*
    258  * ktrace system call
    259  */
    260 /* ARGSUSED */
    261 int
    262 sys_ktrace(curp, v, retval)
    263 	struct proc *curp;
    264 	void *v;
    265 	register_t *retval;
    266 {
    267 	register struct sys_ktrace_args /* {
    268 		syscallarg(char *) fname;
    269 		syscallarg(int) ops;
    270 		syscallarg(int) facs;
    271 		syscallarg(int) pid;
    272 	} */ *uap = v;
    273 	register struct vnode *vp = NULL;
    274 	register struct proc *p;
    275 	struct pgrp *pg;
    276 	int facs = SCARG(uap, facs) & ~((unsigned) KTRFAC_ROOT);
    277 	int ops = KTROP(SCARG(uap, ops));
    278 	int descend = SCARG(uap, ops) & KTRFLAG_DESCEND;
    279 	int ret = 0;
    280 	int error = 0;
    281 	struct nameidata nd;
    282 
    283 	curp->p_traceflag |= KTRFAC_ACTIVE;
    284 	if (ops != KTROP_CLEAR) {
    285 		/*
    286 		 * an operation which requires a file argument.
    287 		 */
    288 		NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, SCARG(uap, fname),
    289 		    curp);
    290 		if ((error = vn_open(&nd, FREAD|FWRITE, 0)) != 0) {
    291 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
    292 			return (error);
    293 		}
    294 		vp = nd.ni_vp;
    295 		VOP_UNLOCK(vp);
    296 		if (vp->v_type != VREG) {
    297 			(void) vn_close(vp, FREAD|FWRITE, curp->p_ucred, curp);
    298 			curp->p_traceflag &= ~KTRFAC_ACTIVE;
    299 			return (EACCES);
    300 		}
    301 	}
    302 	/*
    303 	 * Clear all uses of the tracefile
    304 	 */
    305 	if (ops == KTROP_CLEARFILE) {
    306 		for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    307 			if (p->p_tracep == vp) {
    308 				if (ktrcanset(curp, p)) {
    309 					p->p_tracep = NULL;
    310 					p->p_traceflag = 0;
    311 					(void) vn_close(vp, FREAD|FWRITE,
    312 						p->p_ucred, p);
    313 				} else
    314 					error = EPERM;
    315 			}
    316 		}
    317 		goto done;
    318 	}
    319 	/*
    320 	 * need something to (un)trace (XXX - why is this here?)
    321 	 */
    322 	if (!facs) {
    323 		error = EINVAL;
    324 		goto done;
    325 	}
    326 	/*
    327 	 * do it
    328 	 */
    329 	if (SCARG(uap, pid) < 0) {
    330 		/*
    331 		 * by process group
    332 		 */
    333 		pg = pgfind(-SCARG(uap, pid));
    334 		if (pg == NULL) {
    335 			error = ESRCH;
    336 			goto done;
    337 		}
    338 		for (p = pg->pg_members.lh_first; p != 0; p = p->p_pglist.le_next)
    339 			if (descend)
    340 				ret |= ktrsetchildren(curp, p, ops, facs, vp);
    341 			else
    342 				ret |= ktrops(curp, p, ops, facs, vp);
    343 
    344 	} else {
    345 		/*
    346 		 * by pid
    347 		 */
    348 		p = pfind(SCARG(uap, pid));
    349 		if (p == NULL) {
    350 			error = ESRCH;
    351 			goto done;
    352 		}
    353 		if (descend)
    354 			ret |= ktrsetchildren(curp, p, ops, facs, vp);
    355 		else
    356 			ret |= ktrops(curp, p, ops, facs, vp);
    357 	}
    358 	if (!ret)
    359 		error = EPERM;
    360 done:
    361 	if (vp != NULL)
    362 		(void) vn_close(vp, FWRITE, curp->p_ucred, curp);
    363 	curp->p_traceflag &= ~KTRFAC_ACTIVE;
    364 	return (error);
    365 }
    366 
    367 int
    368 ktrops(curp, p, ops, facs, vp)
    369 	struct proc *p, *curp;
    370 	int ops, facs;
    371 	struct vnode *vp;
    372 {
    373 
    374 	if (!ktrcanset(curp, p))
    375 		return (0);
    376 	if (ops == KTROP_SET) {
    377 		if (p->p_tracep != vp) {
    378 			/*
    379 			 * if trace file already in use, relinquish
    380 			 */
    381 			if (p->p_tracep != NULL)
    382 				vrele(p->p_tracep);
    383 			VREF(vp);
    384 			p->p_tracep = vp;
    385 		}
    386 		p->p_traceflag |= facs;
    387 		if (curp->p_ucred->cr_uid == 0)
    388 			p->p_traceflag |= KTRFAC_ROOT;
    389 	} else {
    390 		/* KTROP_CLEAR */
    391 		if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
    392 			/* no more tracing */
    393 			p->p_traceflag = 0;
    394 			if (p->p_tracep != NULL) {
    395 				vrele(p->p_tracep);
    396 				p->p_tracep = NULL;
    397 			}
    398 		}
    399 	}
    400 
    401 	/*
    402 	 * Emit an emulation record, every time there is a ktrace
    403 	 * change/attach request.
    404 	 */
    405 	if (KTRPOINT(p, KTR_EMUL))
    406 		ktremul(p->p_tracep, p->p_emul->e_name);
    407 
    408 	return (1);
    409 }
    410 
    411 int
    412 ktrsetchildren(curp, top, ops, facs, vp)
    413 	struct proc *curp, *top;
    414 	int ops, facs;
    415 	struct vnode *vp;
    416 {
    417 	register struct proc *p;
    418 	register int ret = 0;
    419 
    420 	p = top;
    421 	for (;;) {
    422 		ret |= ktrops(curp, p, ops, facs, vp);
    423 		/*
    424 		 * If this process has children, descend to them next,
    425 		 * otherwise do any siblings, and if done with this level,
    426 		 * follow back up the tree (but not past top).
    427 		 */
    428 		if (p->p_children.lh_first)
    429 			p = p->p_children.lh_first;
    430 		else for (;;) {
    431 			if (p == top)
    432 				return (ret);
    433 			if (p->p_sibling.le_next) {
    434 				p = p->p_sibling.le_next;
    435 				break;
    436 			}
    437 			p = p->p_pptr;
    438 		}
    439 	}
    440 	/*NOTREACHED*/
    441 }
    442 
    443 void
    444 ktrwrite(vp, kth)
    445 	struct vnode *vp;
    446 	register struct ktr_header *kth;
    447 {
    448 	struct uio auio;
    449 	struct iovec aiov[2];
    450 	register struct proc *p = curproc;	/* XXX */
    451 	int error;
    452 
    453 	if (vp == NULL)
    454 		return;
    455 	auio.uio_iov = &aiov[0];
    456 	auio.uio_offset = 0;
    457 	auio.uio_segflg = UIO_SYSSPACE;
    458 	auio.uio_rw = UIO_WRITE;
    459 	aiov[0].iov_base = (caddr_t)kth;
    460 	aiov[0].iov_len = sizeof(struct ktr_header);
    461 	auio.uio_resid = sizeof(struct ktr_header);
    462 	auio.uio_iovcnt = 1;
    463 	auio.uio_procp = (struct proc *)0;
    464 	if (kth->ktr_len > 0) {
    465 		auio.uio_iovcnt++;
    466 		aiov[1].iov_base = kth->ktr_buf;
    467 		aiov[1].iov_len = kth->ktr_len;
    468 		auio.uio_resid += kth->ktr_len;
    469 	}
    470 	VOP_LOCK(vp);
    471 	error = VOP_WRITE(vp, &auio, IO_UNIT|IO_APPEND, p->p_ucred);
    472 	VOP_UNLOCK(vp);
    473 	if (!error)
    474 		return;
    475 	/*
    476 	 * If error encountered, give up tracing on this vnode.
    477 	 */
    478 	log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
    479 	    error);
    480 	for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
    481 		if (p->p_tracep == vp) {
    482 			p->p_tracep = NULL;
    483 			p->p_traceflag = 0;
    484 			vrele(vp);
    485 		}
    486 	}
    487 }
    488 
    489 /*
    490  * Return true if caller has permission to set the ktracing state
    491  * of target.  Essentially, the target can't possess any
    492  * more permissions than the caller.  KTRFAC_ROOT signifies that
    493  * root previously set the tracing status on the target process, and
    494  * so, only root may further change it.
    495  *
    496  * TODO: check groups.  use caller effective gid.
    497  */
    498 int
    499 ktrcanset(callp, targetp)
    500 	struct proc *callp, *targetp;
    501 {
    502 	register struct pcred *caller = callp->p_cred;
    503 	register struct pcred *target = targetp->p_cred;
    504 
    505 	if ((caller->pc_ucred->cr_uid == target->p_ruid &&
    506 	     target->p_ruid == target->p_svuid &&
    507 	     caller->p_rgid == target->p_rgid &&	/* XXX */
    508 	     target->p_rgid == target->p_svgid &&
    509 	     (targetp->p_traceflag & KTRFAC_ROOT) == 0) ||
    510 	     caller->pc_ucred->cr_uid == 0)
    511 		return (1);
    512 
    513 	return (0);
    514 }
    515 
    516 #endif
    517